Multilayer films and their products are pervasive in modern commercial and consumer applications, due to advantages and synergisms produced by forming layers of different materials into a single composite film. Advantages available with multilayer constructions include mechanical strength, tear or puncture resistance, and desirable optical properties. Multilayer optical products in particular are used in products such as computers, touch screen displays, other electronic devices, window films, diffusers, polarizers, and mirrors, to name a few.
Multilayer products are sometimes formed together (e.g., co-extruded), are sometimes laminated from separate pre-formed film layers into a multilayer film construction, and are sometimes placed together and kept in contact using an adhesive layer that may have optical properties. Certain adhesive materials having optical properties such as good clarity or transmissivity are known, including pressure sensitive adhesives, structural adhesives, and combinations such as structural-pressure sensitive adhesive hybrids.
Certain layers of a multilayer optical product having non-optical functions such as adhesive layers can negatively affect optical properties of a multilayer composite such as clarity, resolution, contrast, or transmissivity, or cause such negative optical effects as ghosting, haloing, or causing an increased reflection of the optical product due to interfacial reflection.
There is ongoing need for optical products with useful and improved optical properties such as high clarity, transmissivity, contrast, resolution, a lack of ghosting or haloing, and low reflectivity, for use in a variety of optical applications.